Hollow blades for compressors



July 17, 1962 E. A. STALKER HOLLOW BLADES FOR COMPRESSORS Filed June 8, 1955 rll mmvrm United States atent O 3,044,152 HOLLOW BLADES FOR COMPRESSORS Edward A. Stalker, Bay City, Mich., assignor to The Stalker Corporation, a corporation of Michigan Filed June 8, 1955, Ser. No. 513,960 2 Claims. (Cl. 29156.8)

This invention relates to hollow blades for compressors, turbines and the like.

An object of the invention is to provide hollow blades having outsidenose radii of very small dimensions relative to the thickness of the blade wall.

Another object is to provide a hollow blade having a thicker wall at the nose than rearward thereof.

A further object is to provide a fabrication process for hollow blades having sharp noses or thickened nose walls.

Other objects will appear from the description, the accompanying drawings and the appended claims.

The above objects are accomplished by the means illustrated in the accompanying drawings in which- FIG. 1 is a side elevation of a blade and stem fabricated by the process of the instant invention;

FIG. 2 is a section on line 22 in FIG. 1;

FIG. 3 is a side elevation of an upsetting machine shown partly in section;

FIG. 4 is a side elevation of an upset blank;

FIG. 5 is a fragmentary vertical section through a stretch forming press;

FIG. 6 is a fragmentary elevation of a nose and wall aligning die and mandrel, partly in section; and

FIG. 7 shows a blade supported in a brazing rack before the trailing edge portion is removed.

In certain types of blade sections the nose is so very sharp that it is difficult to produce while retaining a substantial blade Wall thickness, particularly where the blade envelope is formed from sheet stock or the like. For a disclosure of such a product and process reference is made to co-pending application, Serial Number 282,012 filed by Daniel Jarvis Clarke and Edward A. Stalker, April 12,

1952, now abandoned. It is desirable to have a nose surface which is formed from a sheet integral across the line of folding for the leading edge.

The blade envelope 10 has the contoured upper wall 16 and the contoured lower wall 18 which are formed from an integral sheet of metal.

In order to provide the sharp nose with a radius smaller than the thickness of the blade walls adjacent the leading edge of the blade, a blade envelope blank 20, FIG. 3, is upset between dies to form the sharp nose portion 22 shown in FIGS. 3 and 4.

The die 26, FIG. 3, is fixed to the bed 28 and carries the groove 32 corresponding to the shape of the nose portion of the blade. The blank is positioned between the dies 26 and 34 when the latter is retracted from the former by the toggle linkage and the hydraulic cylinder 42.

With the dies in the position shown in FIG. 3 the plunger 41 is forced down causing the metal to flow into the groove 32. The blank may be either hot or cold. The plunger 41 extends along the length of the blank, that is the direction normal to the plane of the paper.

After the blank is upset the die 34 is retracted to the right and the blank 20 is removed. It then appears as in FIG. 4. However the nose 22 may be straight as well as curved as shown in FIG. 4.

The blank is next put in the stretching press 50 across the recess 52, FIG. 5 The male die 54 presses the blank into the recess and at a locality short of the full stroke of this die the hold-downs 60 and 62 grip the sheet and preferably restrain it from further movement under the hold-downs. The male die 54 may, for instance, be about of an inch from the bottom of its stroke. The die is 3,044,152 Patented July 17, 1962 forced against the sheet for the remainder of the stroke to stretch the sheet to the contours of the die 54 and of the female die 64. The bottom of the recess 52 is further provided with a slot or recess to guide the nose of the blank and properly relate it to the side walls 16 and 18.

The contours of the male die from 70 to 72, FIG. 5, correspond precisely to the selected upper contours of the blade sections. The contours from 74 to 76, formed partly on the male die 54 and partly on the female die 64, correspond precisely to the selected lower contours of the blade sections.

The blank is separated from the portions under the hold-downs by the knives and 82, FIG. 5, which nick the blank and cause it to separate under the tension load.

The blank in the stretched condition and in a condition of controlled internal stress is next placed over a mandrel 90, FIG. 6, where the die 92 presses on the blank and aligns the upper and lower Walls 16 and 18 with the nose portion 22 by a forming or bending operation confined to. a narrow zone immediately adjacent the nose, retaining the preformed contours over the rest of the blade Walls comprising the major part thereof. When the blank is removed fromthe mandrel the upper and lower walls are in contact or close together at the trailing edge portions so that they may be spot-welded together at 96, FIG. 7, without distorting the contours beyond the permissible tolerances.

The stem means 100, FIG. 1, is next inserted in the envelope and is preferably tack-welded at and 112 to fix the envelope and means together.

The blade is supported loosely in a rack 120, FIG. 7, and solder preferably in the form of a wire is placed at 122125. Paste is preferably placed at 126 and 127. The rack and blade are then heated to melt the solder and fuse the parts together preferably in a closed space such as a furnace.

The trailing edge portion of the blade is cut off at 130 FIG. 7, and the raw edge of the blade is de-burred or otherwise faired.

The process also serves to thicken'the leading edge as well as to provide a sharp leading edge. That is a nose of large outside radius could also be provided by this process along with the increased thickness.

The process produces a blade of thickened nose portion free of a joint which is highly advantageous from the point of view of inspection, reliability and cost.

While I have illustrated specific forms of the invention, it is to be understood that variations may be made therein and that I intend to claim my invention broadly as indicated by the appended claims.

I claim:

1. The process of fabricating a hollow blade of selected contours from the nose to the trailing edge thereof com prising the steps of upsetting along the length thereof a sheet metal blade blank of uniform thickness forming an intermediate spanwise thickened blade nose portion having contours corresponding to the-nose portions of said selected contours and of thickness greater than the thickness of said blank adjacent to said nose portion, stretch forming portions of said blank on each side of said nose portion to define upper and lower blade walls in a condition of controlled internal stress having contours corresponding to portions of said selected contours rearward from said nose portion to the trailing edge with said walls spaced apart at their free edges while simultaneously locating said nose portion in relation to said preformed contours, bending said walls in a narrow zone adjacent said thickened nose portion by a die and mandrel acting at said zone to bring said free edges into close proximity while retaining the same selected contours over the major extent of said walls to provide said selected blade section 3 V contours from leading to trailing edges of said blade, and fixing said free edges together to define the trailing edge of said blade.

2. The process of fabricating a hollow blade of selected contours, comprising the steps of upsetting along the length thereof a sheet metal blade blank of uniform thickness forming an intermediate spanwise thickened blade nose portion having contours corresponding to the nose port-ions of said selected contours and of a thickness greater than the thiclmess of said blank adjacent said nose portion, placing the blank across an opening in a recessed first die member, forcing a portion of the blank into the opening by means of a second die member While holding the extremities of the blank fixed in, clamping members with said thickened nose portion being received in a recess in said first die member to draw the blank into a shape conforming to the exterior configuration of the second die member and to the interior configuration of a portion of the first die member thereby forming a blank having upper and lower blade Walls with contours corresponding to portions of said selected contours rearwardly from said thickened nose portion in a condition of controlled internal stress and spaced apart at their free edges while simultaneously locating said nose portion in relation to the preformed contours, aligning said Walls with said thickened nose portion by applying a bending force simultaneously to each of said walls in a narrow zone immediately adjacent the nose portion while interiorl-y supporting said blade at said nose portion only leaving the major portion of said walls substantially unchanged to bring said free edges into close proximity to provide said selected blade section contours from leading to trailing edges of said blade, and fixing said free edges together to define the trailing edge of said blade.

ReferencesCited in the file of this patent UNITED STATES PATENTS 1,665,203 Delf Apr. 10, 1928 2,308,998 Misfeldt J an. 9, 1943 2,422,810 Tiedemann June 24, 1947 2,460,483 Berliner Feb. 1, 1949 2,490,976 Mayne et a1 Dec. 13, 1949 2,514,525 Stullcn July 11, 1950 2,577,336 Larnpton Dec. 4, 1951 2,613,718 Vaughn et a1 Oct. 14, 1952 2,613,910 Stalker Oct. 14, 1952 2,642,263 Thorp June 16, 1953 2,675,208 Weinberg Apr. 13, 1954 2,699,598 Daugherty Jan. 18, 1955 2,723,445 Trautvetter Nov. 15, 1955 2,772,855 Stalker i Dec. 4, 1956 2,799,919 Wilder July 23, 1957 FOREIGN PATENTS 332,011 Italy Nov. 21, 1935 

